Alabama

A tree grows in Delaware, but will it grow in Mobile? (Finch)

View full sizeA reader sent in this picture of a Kousa or Chinese dogwood tree she discovered on a trip to Delaware. (Photo courtesy Gina McMellon)

Q: On a recent trip to Delaware, I discovered a tree named a “Kousa” or “Chinese dogwood.” It has beautiful white dogwood type flowers in the spring, and a round red berry with a pithy orange flesh in the fall that is edible (but not too tasty). I’ve read that it is resistant to the dogwood anthracnose disease. I will attach a couple of photos. My question is: Can we grow this beautiful tree in our Gulf Coast climate?

A: Ever since dogwoods started falling to diseases across much of eastern North America, homeowners have been frantically looking for either a cure or a substitute. The Chinese dogwood is one of those substitutes. But here’s the problem: It may not help you with OUR disease problems, which are very different from the disease problems farther north.

I wouldn’t stop you from trialing the Chinese Kousa dogwoods and letting us know your experience, as long as you recognize that it is a trial. Chinese dogwoods (Cornus kousa) have not performed as consistently in Alabama as some might have hoped — I’ve seen some handsome specimens and some pretty ragged ones.

As for disease resistance, well, you’ve got the wrong disease! The dogwood disease that kousa is famously resistant to is not common in Alabama. The disease, Discula destructiva, is restricted almost entirely to areas north of Alabama with very cold springs, so the fact that Chinese dogwood is resistant to this particular disease won’t help you at all.

Here in south Alabama, we have a host of other diseases and pests that have combined to destroy a high percentage of our coastal dogwood trees, including other anthracnose-like leaf spot diseases, septoria leaf spot, verticilium wilt, crown gall, trunk borers, trunk cankers and (now most severe of all) a form of powdery mildew.

It’s not entirely clear how Kousa measures up in resistance to these other ailments, but research in Auburn shows that Kousa may have a few problems of its own, such as a high susceptibility to bark splitting in areas with fluctuating winter temperatures (and south Alabama is the poster child for fluctuating winter temperatures). Because of this tendency, you’ll want to be particularly careful to plant Kousa in an area where it will be partially protected by a high canopy of trees, and preferably on a north or east facing slope.

What would I do? Well, I’d sure spend some time looking at the gorgeous spring-flowering trees that we KNOW perform well in south Alabama, including coastal silverbell (Halesia diptera var. magniflora), American fringe tree (Chionanthus virginicus), Chinese fringe tree (Chionanthus retusas), the many Asian magnolias and dozens of others. There are other Asian dogwoods that are worth trialing, like the Hong Kong dogwood.

If I had my heart set on trialing something that looked exactly like our native dogwoods, I think I’d spend my time trialing new and perhaps more disease resistant cultivars of the real thing. There’s a lot of new interest in identifying unusually tough native flowering dogwoods — cultivars of our native Cornus florida that have survived for a long while here along the Gulf Coast, where disease and pest pressure is unusually severe.

I’ve had recommendations from growers on two cultivars in particular, Weaver’s White and Madison. I can’t tell you how they’ll perform long-term in the landscape, but they have shown some promising initial disease resistance.

Of course, you’re not likely to find these or any other flowering trees mentioned here at the big box stores. But all of them, including the newer native dogwood varieties, will be available at the Mobile Botanical Gardens plant sale, Oct. 20-23. Put it on your calendar.

How do you control kudzu?

Q: In your recent article on kudzu, you state that kudzu is one of the easiest of the invasive weeds to control. How?

From what I have read it is necessary to remove the crowns and to be sure to get deep enough in doing so. The article I got that from spoke of a less (much less) than 100 percent success rate and noted that it is a lot of manual labor to do it.

What is the easy way? Preferably something to apply as I’m getting a little old and arthritic for hard manual labor on my hands and knees.

Thanks for any enlightenment.

A: There’s lots of nonsense about kudzu. You do not need to remove the crown. In fact, I don’t know of any benefit at all in removing just the crown of the plant (which is where the vine meets the roots at the top of the soil). To get rid of kudzu, you’re either going to have to dig up the monumental roots way underground (which is nearly impossible). Or you’re going to have to starve the roots (which is fairly easy, if you understand that the leaves feed the roots).

If you read those articles carefully, I described how grazing by cattle, horses, goats or others can completely eliminate kudzu in a couple of years. I’ve seen it happen multiple times. The reason is simple: Kudzu, like all green plants, can’t survive unless its leaves collect lots of sunlight. Deprive the plant of sunlight by removing the leaves, and it dies.

In a small area where grazing by horses, cattle or goats isn’t practical, you can imitate that effect in your yard by cutting and removing the vines, then mowing the area regularly, just as if it were a lawn. Within a year or two, the area will in effect be a lawn, with little or no sign of kudzu. As with any rambunctious weed or invasive plant, you have to remove all of the foliage to have an effect, so you may need to cooperate with neighbors, if some is on their property.

On the other hand, you can choose to do it the hard way, which is to use only chemicals, in which case, you will not likely succeed. The only chemical available to homeowners, RoundUp, is not all that effective against kudzu (though it may help “clean up” weak infestations that are already being controlled by grazing or other means). More potent chemicals are not allowed for homeowner usage, which is probably wise. These chemicals effectively sterilize the soil, killing all trees, vines, shrubs and grass in the area, and preventing plants from re-establishing for a year or more after application.

Is there a tasty alternative?

Q: Look, I found a bunch of recipes on the internet for kudzu. Who knew you could eat it? Problem solved!

A: Perhaps you haven’t stopped to consider that there are many edible plants that no one eats. Growing kudzu so that it can be easily harvested is at least half the problem. The other problem is that when you go into a restaurant, your first thought isn’t “how can I rid the world of a noxious weed.” You’re going to eat whatever you’ve gotten used to eating, and I suspect that isn’t kudzu.

Actually, we’ve known that kudzu CAN be a useful and even edible plant ever since it was introduced to the South — and that, not surprisingly, is WHY it was introduced more than a century ago. But there are many challenges to getting kudzu from field to table and into people’s mouths. And neither you nor I will go to the trouble of eating kudzu if it isn’t as good as or better than the foods we’ve already gotten used to. In my experience, kudzu is OK to eat, but I’m not going to pay for it at the Winn Dixie.

So, no, a recipe for kudzu doesn’t solve whatever problem it may pose.

What is this tree in Sicily?

Q: I’m sending you pictures of this tree I saw in Sicily. Could you identify it for me, and give me your thoughts on its survivability in the Mobile area. Where can I buy one?

A: I don’t spend much time identifying Sicilian trees, so I probably couldn’t be sure even if the photos were a little more in focus. But Sicily is in a dry, cool Mediterranean climate that has very little in common with rainy and hot Mobile. It would be one of the last places I’d go looking for trees to put in my Mobile garden.

Is there a picture book of flora?

Q: Can you suggest a good picture book for identifying wild plants in our area (what is edible, can be used for medicinal purposes, etc.)

A: Congratulations and condolences! You live in one of the most biologically diverse areas of the country, and it would be nearly impossible to capture that in a picture book.

It’s relatively easy to produce a wildflower book about New England, because there simply aren’t that many species to picture, and that’s why there are so many easy-to-use picture books up there (well, that, and the fact that there are a lot more New Englanders who’d be willing to pay for a book about wildflowers).

A book that identified, showed pictures of and described the uses for all the plants in southwest Alabama would be the size of a multi-volume encyclopedia. It would have 30 or more species of oaks in it, for example, hundreds of shrubs, and thousands of small flowering plants. That book has not been written, as you might imagine. Many plants we don’t even know well enough to know whether they are edible or medicinal or in some other way useful to people.

There are a few books that sort of tip-toe into the fringes of the subject, with a few pictures and double handful of common local plants. I’ll check to see if they’re still published, and mention them in future columns. They’ll be just enough to whet your appetite.

To determine what plants I’m looking at, I mostly use two sources, both of which are available on the internet: The Flora of North America, and Weakley’s Flora of the Southern and Mid-Atlantic States. Both will be a bit intimidating if you’ve never keyed out plants before, and neither is a picture book. But it’s where people who really want to know what they’re looking at go for information.

Are leaves good for the lawn?

Q: I have a St Augustine lawn in Daphne. We live on a hill going down to the bay. Soil is sandy. I have tons of leaves that I put in my beds throughout fall and winter. I am curious, if I want to leave this rich organic matter on the lawn to help nourish the soil, would you use your mower and just keep chopping up the leaves? Is there any problem for leaving too much leaf material on the lawn throughout the winter, or do the benefits next spring outweigh any risks?

A: As long as the leaves are mowed over and chopped up nicely, I don’t think there are any downsides. The benefits to your lawn will be great, as you’ll effectively be building a deeper layer of topsoil for the grass to grow in each year you do it.

Do mushrooms mean trouble?

Q: For the first time in 50-odd years, I have mushrooms all over my front lawn. What could be the problem?

A: I suppose I should be cautious about answering this until I see your yard. But I can fairly easily predict that you have so many mushrooms because you or your neighbor recently had a tree removed (or at least, you have a tree that’s so badly damaged, it SHOULD be removed).

Mushrooms are simply the reproductive part of a fungus, of course, and fungi often feed on rotting wood. The loss of a tree provides a yard full of dead roots for the fungus to feed on (and tree roots often extend 100 feet or more from the main trunk).

If I’m correct, and you do have a new abundance of dead tree roots, there’s really no problem, since the fungi are simply turning that old wood into good topsoil. Since the fungi are already fruiting (producing mushrooms), they have already extracted most of the nutrients than can from the wood, and will disappear. Your yard will soon be better for it.

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Bill Finch would love to hear about your garden experiences and problems. He can’t answer all questions personally, but you can e-mail him at plaingardening@press-register.com.